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    /**
     * String 字符串
     * Boolean 布尔值
     * Number 数值
     * null 空值
     * undefined 未定义
     * 以上为基本数据类型
     * Object 对象
     **/
    var obj = new Object();
    obj.name = "张三";
    obj.age = 18;
    obj.gender = "男";
    obj.name = "李四";
    //delete(obj.name);
    obj["123"] = "789";
    obj["nihao"] = "yes";
    var a = "nihao";
    var obj2 = new Object();
    obj2.name = "王五";
    obj.test = obj2;
    //in运算符，检查一个对象中是否含有该属性
    console.log("test2" in obj.test);
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